Impulse transmitter



sePf- 1, 1942- F. R. LAMBERTY ETAL 2,294,464

IMPULSE TRANSMITTER Flled April 9, 1958 3 Sheets-Sheet l IID IID .FRLAMBERTV WEWORSG n. WEAVER BV Sept l, 1942. F. R.. LAIMBERTY ETAL 2,294,464

IMPULSE TRANSMITTER Flled April 9, 1938 5 Sheets-Sheet 2 Vr MR mm LW RW FG n W n w NGFQ.

Sept. 1, 1942. F. R. LAMBERTY ETAL 2,294,464

IMPULSE TRANSMITTER F'lled April 9, 1938 I5 Sheets-Sheet 3 .FRLAMBERTY /Nl/EA/TOR .GW WEA VER ATTORNEY Patented Sept. 1, 1942 2,294,464v IMPULSE TRANSMITTER Frederick R. Lamberty, Brooklyn, N. Y., and

George W. Weaver, Westwood,

N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application April 9, 193s, serial No. 201,076

lol. 177-380) 12 Claims.

VThis invention relates to impulse transmitters and more particularly to keyset controlled senders for transmitting series of impulses for setting Selector switches to establish connections to subscribers lines.V

'The present invention is of the general type disclosed in Patent No. 2,002,219 granted May 21, 1935 to T. L. Dimond, whereby a subscriber or an operator at a' private branch exchange or at a manual board of an automatic exchange system may be keying the digits of a desired line designation on a ten-button keyset cause the registration of vsuch keyed digits in a controlling sender which will then function in accordance with the registered digits to set up connections to the desired line.

It is the object of the invention to simplify such sender circuits bythe provision of a single train of relays to serve both as steering relays for successively connecting condenser registers with the keyset and as steering relays for successively connecting the registers with impulse counting equipment during the selection control functioning of the sender and to improve and simplify the impulse .counting equipment where# i by it may serve not only to control the impulse series transmitted in accordance with digit registrations, but also to measure off delay intervals between the transmission of successive impulse series. V

In accordance with the invention it is proposed to employ a group of condensers serving as registers for recording the successive digits keyed and to employ a gas-filled tube controlled successively by the condensers for counting the impulses in each series transmitted by the sender. The condensers are successively connected to the keyset by a train of steering relays which are operated in succession in response to the successive depression and release of keys of the keyset, each condenser being charged to a degree commensurate with the Value of the digit being keyed at the time such condenser is associated with the keyset.

Two condenser timed impulsing relays are provided, one of which transmits impulses for the setting of selector switches and the other of which generates impulses for impulse counting. The impulse counting device, as previously stated, comprises a gas-filled tube which is of such a character that it breaks down or becomes conducting when the potential on its control or grid element is raised to a critical value.

For controlling the transmission of series of impulses in accordance' with the digits of a keyed 55 line designation registered on the register condensers, the impulse counting device including the tube is successively associated with the condensers by the successive release of operated steering relays. When the impulsing starts for any digit series,V a condenser, which will be termed a bucket condenser, connected to the grid of the tube, is associated with the register condenser corresponding to the digit being transmitted whereby the potential across the bucket condenser and the serially connected register condenser is raised to the potential of the register condenser.

Associated with the bucket condenser is a further condenser, termed a dipper condenser, which under the control of the impulse generating relay is alternately charged to a denite potential and then discharged into the bucket condenser thus raising the potential across the terminals of the bucket condenser by predetermined increments and consequently raising the potential on the grid of the tube by the same increments until such condenser has received su'icient increments to raise the total charge across the bucket condenser and serially connected register condenser to ten increments whereupon the tube will flash and will'operate an anode relay to arrest further operation of the pulsing relays, to restore the tube to its normal condition vand to prepare circuits for measuring a delay interval before transmitting the next digii-l series. Duringthe measuring of a delay interval the bucketcondenser is disassociated from any register condenser, but the dipper condenser is alternately charged and discharged into the bucket condenser until the bucket condenser has accumulated a charge equal to the breakdown potentialof the tube whereupon the tube will fire to operate the anode relay to terminate the time interval and to prepare the sender circuit for out-pulsing in accordance with the next registered digit.

During'out-pulsing for successive digits the operated steering relays are successively released to-associate successively charged register condensers with the bucket condenser and the grid of the tube, provision being made to arrest outpulsing whenever the time interval following the out-pulsing for the last digit keyed and registered on a register condenser has been terminated.

The features of the invention will be more clearly apparent from a consideration of the following detailed description read in connection with the accompanying drawings which illustrate the employment of the invention at a subscribers station associated with an automatic telephone exchange system of a type in which the selective operations are controlled by the transmission of series of impulses corresponding to a wanted line designation when it is desired to permit such subscriber to set up connections by keying rather than by dialing digits.

It is to be understood, however, that the invention is not so limited in its use, but may be employed at the operators position of a private branch exchange system or at an A operators position of an automatic exchange system.

Referring to the drawings:

Fig. 1 shows a calling subscribers substation circuit and associated keyset, the diagrammatic illustration of a called line and selector switches for establishing a connection from the calling subscribers line to such called line and a portion of the sender equipment;

Fig. 2 shows further relay equipment of the sender; and

Fig. 3 shows the register condensers and steering relays of the sender.

The complete circuits illustrating the invention will be best visualized by placing Fig. 2 beneath Fig. 1 and Fig. 3 beneath Fig. 2 with the conductors extending to the upper and lower margins thereof in alignment.

The keys of the keyset have digital values of l to 0, inclusive, and are of the non-locking type. Steering relays 30| to 309, inclusive, of Fig. 3, serve to connect the digit register condensers 3H to 3|8, inclusive, one at a time and in rotation to the keys of the keyset |00 at which time each condenser receives a charge corresponding to the digital value of the particular digit keyed and also serve to connect the charged condensers one at a time and in rotation with the bucket condenser |30 associated with the grid or control electrode of the gas-filled tube ||0.

It is believed that the invention will be best understood from a detailed description of the establishment of a connection initiated from the substation |0| of a calling line to the called line |02, it being assumed that for this purpose the calling subscriber keys the number 3498.

When the calling subscriber at substation 0| removes the handset from the switchhook cradle, ground is connected over the lower contacts of the cradle contact assembly to conductor |03 thereby completing the operating circuit of relay 200 and applying ground to the outer right contacts of the keys of the keyset |00, and the substation loop is closed through the station line circuit for starting the line nder |04 to search for the calling line in the usual manner. Relay 200 upon operating establishes a circuit from battery, over its inner lower contact, conductor |05 and resistance I 06 through the iilament ||2 of tube l l0; establishes a circuit from battery over its lowermost contact, resistance 20|, conductor 202,

thence in series through the upper windings of pulsing relays |01 and |08, through resistance |03, conductor M, middle lower contact of relay 200 to battery; establishes a charging circuit for condenser 203 extending from ground, through the condenser, inner upper front contact of relay 200, conductor 200, thence serially through the lower windings of relays |01 and |08, through resistance |09, conductor ||4 to battery over the middle lower contact of relay 200, and at its upper three contacts connects holding ground to conductors 5, 205 and 2|5. Condenser 203 charges in the previously traced circuit and the charging current flowing through the lower windings of pulsing relays |01 and |08 causes their operation at this time to engage their armatures with their left contacts if they are not in engagement therewith.

When the subscriber depresses the No. 3 key H6 to record the rst digit of the assumed called line designation, a circuit is established from the battery through the winding of relay 200, conductor 201, right contacts of key I I6 to ground on conductor |03 and relay 206 operates establishing a circuit from battery through the winding of relay 208, back contact of relay 209, lower back contact of relay 2 l0, lower contact of relay 206 to ground on conductor 20E. Relay 208 operates and locks in a circuit from battery through its winding, back contact of relay 200, front contact of relay 208, upper winding of relay 2|0 to ground on conductor 205, but relay 2|0 does not operate in this locking circuit since its upper winding is shunted s0 long as relay 200 remains operated. Relay 200 also bridges the volt battery 2| across the serially connected resistances ||8 to |28, inclusive, of a potential divider associated with the keyset |00 over a circuit extending from the lower terminal of resistance ||8 and conductor |3| to the positive terminal of battery 2|| and from the negative terminal thereof over conductor 2|2, the outer upper contact of relay 205, conductor |32 to the junction between resistances |28 and |23. The other junctions between the resistances of the potential divider are connected to the outer left contacts of the keys of theY keyset |00.

With the No. 3 key H6 depressed and relay 200 operated, potential is applied across the terminals of register condenser 3H from the potential divider. The left terminal of condenser 3|| being connected over conductor 2| 2, the upper contacts of relay 200 and conductor |32 to the junction between resistances |28 and |29 and the right terminal of the condenser being connected over the upper back contact of steering relays 30| to 304, inclusive, the lower back contacts of steering relays 305 to 309, inclusive, conductor 3| 0, inner upper contacts of relay 206, conductor |1, left contacts of key ||6 to the junction between resistances |2| and |22. Condenser 3|| is thus charged to a potential equal to the drop across the resistances |22 to |28, inclusive, or with seven increments of potential.

When the operator releases the depressed key I0 the charging path for condenser 3| i is opened at its left contacts and the operating circuit of relay 200 is opened at its right contacts. Relay 200 now releases, opening the shunt `around the upper winding of relay 2|!) which now operates in the locking cincuit of relay 208 and establishes a circuit for steering relay 30| which may lbe traced from battery through the winding of relay 30|, thence serially over the lower back contacts of relay 300 and steering relays 302 and 304, serially over the upper back contacts of steering relays 305 and 308, `conductor 3|9, upper `front contact of relay 2H) to ground on conductor 205. Relay 30| upon operating locks in a circuit from battery through its winding and inner upper front contact, over conductor 32|, lower normal contacts of relay 2|3 to ground on conductor 2|5; opens at its upper back contact the charging `circuit for register condenser 3| previously traced; prepares at its upper front :contact the charging circuit for register condenser 3| 2 prepares at its middle upper front Ybe traced from contact a discharge path for condenser 3||; closes `a shunt around the winding of relay 2|9 vand establishes an operating circuit for oli-normal relay 300.

The shunt around the winding of relay 2|9 may be traced from the right terminal of the winding of relay 2|9, over conductor 2|5, lower normal contacts of relay 2|3, conductor 32|, inner upper and inner lower front contacts of relay 30|, thence serially through the inner lower normal contacts of relays 302 to 304, inclusive, serially through the inner upper normal contacts of relays 305 to 309, inclusive, conductor 320 to the left terminal of the winding of relay 2|9. The operating circuit of relay 300 may 'be traced from battery through the winding and inner lower normal contacts of relay 300, middle lower front contact of relay 30| to ground on conductor 2|5.

Relay 300 upon operating locks over its inner lower alternate .contacts to ground on conductor 2|5; opens at its lower back contact the initial operating cincuit of steering relay 30|; connects ground from conductor 2|5 over its middle lower front contact, conductor 22|, through resistance 222 to conductor 202 and thence to the left terminlal of the upper winding of pulsing relay |01 for starting the operation of the pulsing relays |01 and |08 as will be presently described and connects battery 2|| across the pulsing potential divider comprising resistances |30, |40 and Ml, the positive terminal of battery 2H being iconnected over conductor |3| to the left terminal of resistance |39 and the negative` terminal of the battery being `connected over conductor 2|2, the upper contact of relay 300, conductor 229, through resistance 226 and conductor |42 to the right terminal of resistance |4|.

Relay 300 also 'closes circuits for relays 2|6 and 2i1 extending from battery through resistance 223, winding of relay 2|1 and in parallel therewith from battery through resistance 224 and winding of relay 2|6, thence through the inner upper normal contacts of relay 2|6, back contact of anode relay 2|8, back contact off relay 2|9, conductor 220 and the lower front Contact of relay 300 to ground on conductor 2|5. Relay 2| operates, but the winding or relay 2|1 being shunted at this time by ground applied over the inner upper normal contacts of relay 2|6 and i over the inner upper back Contact of relay 2|1 to the junction between resistance 223 and the winding of relay 2|1, does not operate at this time. Relay 246 upon operating locks over its upper inner alternate contacts, back contact of relay 229, conductor 220, lower front contact of relay 300 to ground on conductor 2|5 and establishes an operating circuit for relay 225 which may 'be traced from battery through the winding of relay 225, lower rfront contact of relay 2|0, lower back contact of relay 2|1 to ground on conductor 2|5 for performing functions to be later described.

The subscriber has in the meantime proceeded to depress another key of the keyset to record the second digit of the desired line designation. Since it has been assumed that the second digit was 4, he will depress the No. 4 key |33 whereupon relay 266 will again operate as previously described, and with relays 208 and 2|0 at the time operated, will establish an operating circuit for relay 209 which -circuit may battery through the winding of relay-2,09, the lower winding and lower front contact of relay 2,50, the lower contact of relay 206 to ground on conductor 205. Relay 209 upon operating opens the locking circuit of relay 208 previously traced through the upper winding of relay 2|0 and relay 208 thereupon releases, but Arelay 2|0 is maintained operated over its lower winding in series with the winding of relay 209.

With steering relay 30| operated, the operation of relay 206 now applies potential across the terminals of register condenser 3|2 from the keyset potential divider, the lower terminal of condenser 3|2 being connected over the inner upper Ifront contact of relay 300, conductor `2|2, the -upper contacts of relay 206, conductor |32 to the junction between resistances |28 and |29, and the upper terminal of the condenser being connected over the upper front contact of steering relay 30|, the upper back contacts of steering relays 302 to 304, inclusive, the lower black contacts of steering relays `305 to 309, inclusive, conductor 3|0, inner upper 'contacts of relay 206, conductor ||1, left lcontacts of key |33 to the junction 'between resistances |22 yand |23. Condenser 3|2 is thus charged to `a potential equal to the drop across resistances |23 to |28, inclusive, or with six increments of potential.

When the subscriber releases the depressed key |33, the charging path for condenser 3|2 is opened at its left contacts and the operating circuit of relay 200 is opened at its right contacts. Relay 206 now releases opening the operating circuit of relay 209 and the locking circuit of relay 2|0 whereupon these relays release, relay 2|0 upon releasing establishing an operating circuit for steering relay 302. This circuit may be traced from battery, through the winding of relay 302, the lower front contact of steering relay 30 the lower back contact of steering relay 303, the upper back contacts of steering relays 305, 301 and 309, conductor 322, the upper back contact of relay 2|0 to ground on conductor 205. Relay 302 upon operating locks in a circuit from battery through its winding and inner upper front contact, middle lower front contact of relay 30| to ground on conductor 2|5; opens at its upper back contact the charging circuit-forregister condenser 3|2 previously traced; prepares at its upper front contact the charging circuit for register condenser 3|3; prepares at its middle upper front contact a discharge path for condenser 3|2 and establishes a new shunt around the winding of relay 2|9 extending as previously traced from the left terminal of relay 2|0 to the inner lower normal contacts of relay 303, thence over the inner lower and inner upper front contacts of relay 302, middle lower front contact of relay 30|, conductor 2|5 to the right terminal of relay 2I6, The previously traced shunt of relay 2|9, established by the operation of relay 30|, is now opened at the inner lower contacts of relay 302.

When the subscriber depresses the No. 9 key |34 to record the third digit, assumed to be 9, relay 206 will again operate and with relays' 209 and 2|0 now released, relay 208 operates as described in connection with the recording of the rst keyed digit and locks through the upper winding of relay 2|0, but the winding of relay 2|0 being shunted, relay 2|0 does not operate. With steering relay 302 operated, the operation of relay 200 now applies potential across the terminals of register condenser 3|3 from the keyset potential divider, the lower terminal of condenser 3|3 being connected over the inner upper front contact of relay 300, conductor 2 |2, the upper contacts of relay 206 and conductor |32 t0 the junction between resistances |28 and |29 and the upper terminal of the condenser being connected over the upper front contact of steering relay 302, the upper back contacts of steering relays 303 and 304, the lower back contacts of steering relays 305 to 300, inclusive, conductor 3|0, inner upper contacts of relay 200, conductor ||1, left contacts of key |34 to the junction between resistances |21 and |28. Condenser 3|3 is thus charged to a potential equal to the drop across resistance |28 or with one increment of potential.

When the operator releases depressed key |34, the charging path for condenser 3|3 is opened at its left contacts and the operating circuit of relay 200 is opened at its right contacts. Relay 206 now releases removing the shunt from the winding of relay 2|0 which now operates in the locking circuit of relay 208 and establishes an operating circuit for steering relay 303 which may be traced from battery through the wind ing of relay 303, the lower front contact of steering relay 302, the lower back contact of relay 304, the upper back contacts of relays 300 and 308, conductor 3| 9, the upper front Contact of relay 2|0 to ground on conductor 205. Relay 303 upon operating locks in a circuit from battery through its winding and inner upper front con tact, middle lower front contact of relay 302 to ground on conductor 2 I5; opens at its upper back contact the charging circuit for register cone denser 3|3; prepares at its upper front contact the charging circuit for register condenser 3HE; prepares at its middle upper front contact the discharge path for condenser 3|3 and establishes a new shunt around the winding of relay 2 i9, eX- tending as previously traced from the left terminal of relay 2 9 to the inner lower normal contacts of relay 304, thence over the inner lower and inner upper front contacts of relay 303, the middle lower front contact of relay 302, conductor 2|5 to the right terminal of relay 2|9` The previously traced shunt of relay 250, established by the operation of relay 302, is now opened at the inner lower contacts of relay 303.

When the subscriber depresses the No. 8 kei7 |35 to record the fourth digit, assumed to be 8, relay 206 will again operate and with relays 200 and 2|0 at the time operated, will establish the operating circuit for relay 208 as previously traced. Relay 200 upon operating opens the locking circuit of relay 208 previously traced through the upper winding of relay 2|0 and relay 208 thereupon releases, but relay 2| 0 is maintained operated over its lower winding in series with the winding of relay 200.

With steering relay 303 operated, the operation of relay 206 now applies potential across the terminals of register condenser 3|4 from the keyset potential divider, the lower terminal of condenser 3|4 being connected over the inner upper front contact of relay 300, conductor 2| 2, the upper contacts of relay 200, and conductor |32 to the junction between resistances |28 and |20 and the upper terminal of the condenser being connected over the upper front contact oi steering relay 303, the upper back contact of steering relay 304, the lower back contacts of steering relays 305 to 309, inclusive, conductor 3|0, the inner upper contacts of relay 200, conductor ||1, left contacts of key |35 to the junction between resistances |20 and |21. Condenser 3|4 is thus charged to a potential equal to the drop across resistances |21 and |28, or with two increments of potential.

When the subscriber releases the depressed key |35 the charging path for condenser 3|4 is opened at its left contacts and the operating circuit of relay 200 is opened at its rightl contacts. Relay 206 now releases opening the operating circuit of relay 209 and the locking circuit of relay 2|0 whereupon these relays release, relay 2|0 upon releasing establishing an operating circuit for steering relay 304 which may be traced from battery through the winding of relay 304, the lower front contact of steering relay 303, the upper back contacts of steering relays 305, 301 and 309, conductor 322, the upper back contact of relay 2|0 to ground on conductor 205. Relay 304 upon operating locks in a circuit from lbattery through its winding and inner upper front contact, middle lower front contact of relay 303 to ground on conductor 2|5; opens at its upper back contact the charging circuit for register condenser 3|4; prepares at its upper front contacts the charging circuit for register condenser 3|5; prepares at its middle upper front contact a discharge path for condenser 3|4 and establishes a new shunt around the winding of relay 2| 0 extending as previously traced from the left terminal of relay 2|9 to the inner upper normal contacts of relay 305, thence over the inner front contacts of relay 304, the middle lower front contact of relay 303 and conductor 2E5 to the right terminal of relay 2|0. The previously traced shunt of relay 2|0, established by the operation of relay 303, is now opened at the inner lower contacts of relay 304.

It will be noted from the foregoing description that relays 208, 209 and 2|0 function in response to the operation and release of relay 200 in such a manner that relay 2|0 is operated following the termination of keying of each odd digit and is released following the termination of keying of each even digit.

All of the digits of the assumed line number have now been registered by the charged condition of condensers 3H to 3M, inclusive. In the meantime and as soon as the rst keyed digit was recorded as indicated by the operation of steering relay 30|, ofi-normal relay 300, relay 2|0 and relay 225, outpulsing for the first digit was initiated. When relay 300 operated and connected ground through resistance 222 to the left terminal of the winding of pulsing relay |01, an energizing circuit through the upper windings of relays |01 and |08 and resistance |09 was completed over conductor ||4 and a contact of relay 200 to battery and the pulsing relays thereupon operated their armatures into engagement with their right contacts. With relay 225 now operated ground is connected from conductor 2 l5 over the upper front contact of relay 225 to the armature of relay |08 and a discharge path for condenser 203 is established from ground on the armature of relay |08 over its right contact, through the lower windings of relays |01 and |08, conductor 204, the inner upper contact of relay 200, through condenser 203 to ground and condenser 203 discharges thereover. At the same time ground applied over the armature and right contact of relay |08 through the upper windings of relays |01 and |08, over conductor 202, resistance 222, conductor 22| and the middle lower contact of relay 300 to ground on conductor 2|5. short-circuits the upper windings of relays |01 and |08. cuited, the discharge current from condenser 203 energizes the lower windings of relays |01 and |08 in such a direction as to cause these relays With their upper windings shirt-cir-Y to move their armatures into engagement with their left contacts.

When the armature of relay |08 leaves its right contact the shunt around the upper windings of relays |01 and |08 is opened and these windings again energize and the previously traced charging circuit for condenser 203 is again established. Since relays |01 and |08 are differentially wound, the ux set up by the energization of their upper windings is opposed by the flux set up by the charging current for condenser 203 flowing through their lower windings. When the charging current through the lower windings decays, however, the upper windings take control and relays |01 and |08 move their armatures into engagement with their right contacts. In this manner relays |01 and |08 continue to operate their armatures from their right to their left contacts at a rate determined by the charging and discharging times of condenser 203, or at a rate determined by the best conditions for the transmission of selector setting impulses.

Relay 225 upon operating in addition to controlling the operation of the pulsing relays |01 and |08, opens at its upper back contact a discharge circuit through resistance condenser |30; closes a shunt over its inner lower front contact around resistance 226; connects the positive terminal of battery 2|| through the winding of anode relay 2|8, the middle lower front Contact of relay 225, the lower back contact of relay 221 and conductor 228 to the anode ||3 of tube and connects the potential divider comprising resistances |30, |40 and |4| without the inclusion of resistance 220 in series across the terminals of battery 2||, the left terminal of resistance |39 being connected over conductor |31 to the positive terminal of battery 2|| and the right terminal of resistance |4| being connected over conductor |42, the inner lower contact of relay 225, conductor 229, the upper contact of relay 300, conductor 2|2 to the negative terminal of battery 2||.

Upon the rst operation of the armature of pulsing relay |01 to the right a shunt is established around the right normal contacts of relay |54 and when relay |01 again operates its armature to the left this shunt is opened, but without effect since relay |54 has not yet operated and consequently the line loop extending over conductors |30 and |31 to the line relay (not shown) of the rst selector |43 is not interrupted to cause the vertical stepping of the rst selector. When pulsing relay |08 iirst engages its armature with its left contact following the operation of relays 2|6 and 225, a circuit is established for operating relay 221 which may be traced from battery through the winding of relay 221, the lower back contact of relay 230, the upper front contact of relay 2|0, conductor 23|, the left contact of pulsing relay |08, the upper front contact of relay 225 to ground on conductor 2|5. Relay 221 upon operating locks over a circuit in series with the winding oi relay 230, the upper front contact of relay 221, the lower front contact of relay 225, to ground on conductor 2|5, butrelay 230 does not operate in this locking circuit so long as pulsing relay |00 holds its armature on its left contact. Relay 221 also closes a circuit for relay |44 extending from ground on conductor |03 through the winding of relay |44, conductor |45, over the lower front contact of relay 221 to battery and relay |44 operates to open the receiver circuit at the substation duringv impulsing.

| for bucket |01 and |08 again engage their their right contacts, the shunt around the winding of relayv 230 is opened by relay |08 and relay 230 operates in the locking circuit of relay 221 and establishes the operating circuit of relay |54 which may be traced from battery, through the winding of relay |54, conductor |46, inner upper front contact ofA relay 230, upper back contact of relay 211 to ground on conductor 2|5. Relay |54 upon operating opens the shunt around the contacts of pulsing relay |01 and establishes an impulsing loop from tip conductor |31, over the right alternate contacts of relay |54, the right contact of pulsing relay |01 to ring conductor |36 preparatory to impulsing and at its outer left contacts establishes a new circuit for applying positive potential to the anode ||3 of the tube ||0 replacing the circuit previously traced over the back contact of relay 221. This circuit extends from the positive terminal of battery 2|I, through the winding of relay 2|8, the middle lower contact of relay 225, conductor 232, outer left contacts of relay |54 to the anode ||3.

With relay 230 operated a circuit is established from the grid of the tube, through resistance |48, bucket condenser |30, normal contacts of key |49, conductor 230, upper front contact of relay 230, conductor 233, the middle upper front contact of steering relay 30|, condenser 3|I, upper contact of relay 300, conductor 229, inner lower front contact of relay 225, conductor |42, resistances |4| and |40 of the pulsing potential divider to the adjustable ground whereby the discharged bucket condenser is connected in series with the register condenser 3|| assumed to be charged with seven increments of potential.

On the next operation of the armatures of pulsing relays |01 and |08 into engagement with their left contacts, relay |01 opens the outpulsing loop to transmit one impulse to the rst selector switch |43 and relay |08 establishes a circuit from ground on its armature, over its left contact, conductor 23|, the upper front'contact of relay 2|6, the lower front contact of relay 230, conductor 234, winding of secondary pulsing relay |41 and resistance |50 to battery. Relay |41 operates and at its right front contact establishes a holding circuit for relay |54 extending from battery through the winding and inner left front contact of relay |54, right front contact of relay |41 to ground on conductor ||5 and at its left front contacts establishes a charging circuit for dipper condenser |5| extending from the positive terminal of battery 2| I, over conductor |3|, the outer left front contact of relay |41, resistance |52, condenser |5|, the inner left front contact of relay |41, conductor 2|2 to the negative terminal of battery 21|. Condenser |5| is of such capacity that it now charges to a potential substantially equal to one increment of the potential previously applied during the keying operation across the terminals of register condenser 3| As soon as pulsing relays |01 and |08 again move their armatures to the right, relay |01 again closes the out-pulsing loop to terminate the rst transmitted impulse and relay |00 opens the operating circuit of secondary pulsing relay |41 which releases, opening the charging circuit of dipper condenser |5| and connecting the dipper condenser over its left front contacts in parallel with bucket condenser |30. Condenser |5| now discharges into condenser |30, raising thev potential thereof by one increment. Upon,

When relays armatures with successive operations of the armatures of pulsing relays |01 and |08 first to the left and then to the right, the out-pulsing loop is opened and closed and secondary pulsing relay |41 is operated and released to charge dipper condenser |5| and to discharge it into bucket condenser |30. After relay |01 has thus opened and then closed the out-pulsing loop three times and relay |08 has operated and then released pulsing relay |41 three times, three increments of potential will have been applied to bucket condenser |30 at which time the total potential across the terminals of condensers |30 and 3|| will be ten increments. This total potential applied to the grid of tube 0 will cause the tube to break down establishing a discharge path for condensers |30 and 3| through the tube extending from the grounded cathode |2 to the grid through resistance |48, condenser |30, thence as traced through register condenser 3| I, over the upper contact of relay 300, conductor 220, inner lower contact of relay 225, conductor |42, through resistances 4| and |40 of the potential divider to ground and establishing a conducting path through the tube from the cathode to the anode. This latter circuit may be traced from ground over the cathode-anode path of the tube, thence as traced through the winding of anode relay 2| 3 to the positive terminal 0I battery 2|| and from the negative terminal of battery, conductor 2|2, upper contacts of relay 300, conductor 229, inner lower contact of relay 225, conductor |42, resistance |4| to ground at the adjustable point on resistance |40.

Relay 2|8 operates, establishing a circuit from the junction between the winding of secondary pulsing relay and resistance |50 over the right back contact of relay |41, conductor |53, front contact of relay 2|8, back contact of relay 2|9,

conductor 220, lower front contact of relay 300 to ground on conductor 2| 5 to shunt the winding of relay |41 and thus prevent its further operation on subsequent closures of the left contact of pulsing relay |08 and, at its back contact opens the shunt previously traced around the winding of relay 2|1, Relay 2|1 now operates, opens at its upper back contact the circuit of relay |54 which thereupon releases to shunt the pulsing contacts of pulsing relay |01 thereby rendering the further operation of pulsing relay |01 ineffective to transmit impulses to the first selector |43; at its lower back contact opens the circuit of relay 225 which then releases and closes a circuit for relays 2|4 and 2|3 in parallel extending from battery through resistance 235, winding of relay 2|3 and from battery through resistance 230, winding of relay 2|4, thence over the normal contacts of relay 2|4, lower front contact of relay 2 |1 to ground on conductor 2 |5.

Relay 2|4 operates over the previously traced circuit and locks over its alternate contacts to ground on conductor 205, but relay 2|3 being shunted by ground applied from conductor 2|5 over the lower contacts of relay 2|1 and its own upper back contact to the junction between its 6 winding and resistance 235, does not operate so long as relay 2|1 remains operated. Relay 225 upon releasing closes at its upper back contact the resistance shunt around bucket condenser |30 to fully discharge the condenser; at its upper front contact removes ground from the armature of pulsing relay |08 thereby arresting the further operation of pulsing relays |01 and |08; at its inner lower contact removes the shunt from resistance 225; at its middle 75 lower contact opens the cathode-anode circuit through the tube thereby extinguishing the tube and releasing anode relay 2|3 and at its lower contact opening the locking circuits of relays 221 and 230 which thereupon release. Relay 221 upon releasing in turn releases relay |44 to again close the substation receiver circuit.

Relay 2|8 upon releasing removes the shunt from the winding of secondary pulsing relay |41 and at its back contact esta-blishes a shunt circuit for shunting down relay 2|0, which circuit may be traced from ground on conductor 220, back contact of relay 2|9, back contact of relay 2|8, inner upper front Contact of relay 2|1 to the junction between the winding of relay 2|6 and resistance 224. Relay 2|6 now releases closing a holding circuit for relay 2|1 extending from battery through resistance 223, winding of relay 2|1, inner upper normal contacts of relay 2| 6, back contact of relay 2|3, back contact of relay 2|9 to ground on conductor 220. With relay 2|1 operated an operating circuit for relay 225 is reestablished from battery through the winding of relay 22 5, lower back contact of relay 2|6, inner lower front contact of relay 2|1 to ground on conductor 2|5. Relay 225 upon operating again removes the shunt from bucket condenser |30, connects ground to the armature of pulsing relay |08 to cause relays |01 and |08 to again operate intermittently as previously described, reconnects the positive terminal battery 2|| through the winding of anode relay 2| 8 to the anode of tube ||0 and again shunts resistance 226.

As soon as pulsing relay |00 engages its left 'contact a circuit is established from ground on the armature thereof over the left contact, conductor 23|, the upper back contact of relay 2|6, the upper front contact of relay 2|1, conductor 234, through the winding of relay |41 and resistance |50 to battery and relay |41 operates to close the previously traced charging circuit for dipper condenser |5|. On the next operation of the armature of pulsing relay |08 to its right contact, relay |41 releases and as previously described, connects the dipper condenser |5| in a discharging path to bucket condenser |30. As relay |08 continues to operate, the dipper condenser |5| is alternately charged and discharged into condenser |30 until the potential across condenser |30 reaches the -breakdown potential of tube ||0 whereupon the tube res establishing a discharge path for condenser |30 from ground on the cathode I| 2, through the tube to the grid I| thence through resistance |48, condenser |30, normal contacts of key |49, conductor 230, upper back contact of relay 230, conductor 238, through resistance |40 to ground andestablishing the cathode-anode circuit through the tube thereby reoperating the anode relay 2| 8. The time required to raise the potential on the grid of tube ||0 to the breakdown point thus measures a sufiicient delay interval to give the iirst selector |43 time to perform its trunk hunting function. During this interval due to the fact that relay |54 is not operated, the repeated operation of pulsing relay |01 is without effect.

When anode relay 2 I8 operates, it again shunts relay |41 in its non-operated position and opens the locking circuit of relay 2|1 which thereupon releases, opening at its lower contact the shunt around the winding of relay 2|3 thereby permitting the operation of relay 2| 3 and opening the circuit of relay 225 which thereupon releases.

Relay 225 upon releasing reestablishes the discharge shunt around condenser 130, removes ground from the armature of pulsing relay 108 to arrest the operation of pulsing relays 101. and 108 and opens the cathode-anode circuit through tube 110 to extingush the tube and to releane anode relay 218.

Relay 218 upon releasing removes the shunt from the winding of the secondary pulsing relay 141 and establishes a circuit for reoperating relay 216 which may be traced from ground on conductor 220, back contact of relay 219, back contact of relay 218, normal contacts and Winding of relay 216, through resistance 224 to battery. With relay 216 operated and relay 211 released the previously traced operating circuit for relay 225 is established and relay 225 reoperates to remove the shunt from condenser 130, to restart the operation of pulsing relays 101 and 108 and to connect the positive terminal of battery 211 through the winding of anode relay 218 to the anode of the tube. Upon the first engagement of the armature of pulsing relay 108 with its left contact, with relays 216 and 225 now operated, the circuit of relay 221 is established from battry, through the winding of relay 221, lower back contact of relay 230, upper front contact of relay 218, conductor 231, left contact of relay 108, upper front contact of relay 225 to ground on conductor 215 and relay 221 operates, again es tablishing the operating circuit of relay 144 and closing a previously traced locking circuit for itself extending through the winding of relay 238. Relay 230 operates in this locking circuit as soon as pulsing relay 108 opens its left contact, causing the reoperation of relay 154 which thereupon renders the pulsing contacts of pulsing relay 101 effective for transmitting impulses to the second selector switch 155.

Relay 213 upon operating opens at its lower transfer contacts the locking circuit of steering relay 381 which thereupon releases and establishes a new holding circuit for steering relay 302 to replace the holding circuit therefor previously traced over the middle lower front contact of steering relay 381. The new holding circuit for relay 352 may be traced from battery through the winding and inner upper front contact of relay 302, conductor 323, lower alternate contacts of relay 213 to ground on conductor 215. The release of steering relay 301 disconnects the register condenser 311 from the impulse counting device and associates register condenser 312 therewith.

With relay 230 operated a circuit is established from the grid 1&1 of the tube through resistance 148, condenser 13B, normal contacts of key 149, conductor 239, upper front contact of relay 230, conductor 233, the upper middle back contact of steering relay 381, the upper middle front contact of steering relay 382, condenser 312, upper contacts of relay 330, conductor 229, inner lower front contact of relay 225, conductor 142, resistances 141 and 148 to ground at resistance 140 whereby condensers 130 and 3i2 are connected in series.

On the next operation of the armatures of pulsing relays 101 and 108 to the left, relay 101 opens the out-pulsing loop to transmit one impulse to the second selector 155 and relay 188 establishes the circuit previously traced over the upper front contact of relay 216, the lower front contact of relay 230 and conductor 234 for operating the secondary pulsing relay 141 which closes the charging circuit of dipper condenser 151. On

the next operation of the armatures of relays 101 and 108 to the right, relay 101 recloses the outpulsing loop to terminate the rst transmitted impulse and relay 108 opens the circuit of relay 141 which now releases and connects condenser 151 into a discharge path through the condenser 130. Upon successive operations of the armatures of pulsing relays 101 and 108 rst to the left and then to the right, the out-pulsing loop is opened and closed and relay 141 is operated and released to charge condenser 151 and to discharge it into condenser 130. After relay 101. has thus opened and then closed the out-pulsing loop four times and relay 108 has operated and released relay 141 four times, four increments of potential will have been applied to condenser at which time the total potential across the terminals of condensers 130 and 312 will be ten increments, since it was assumed that condenser 312 was charged With six increments. This total potential applied to grid 111 of the tube will cause the tube to break down establishing a discharge path for condensers 130 and 312 across the cathode and grid as previously described and establishing a conducting path through the tube from the cathode to the anode as previously traced over which the anode relay 218 is operated.

Relay 218 upon operating again shunts relay 141 in its non-operated position and at its back contact opens the shunt around the winding of relay 211. Relay 211 now operates opening at its upper back contact the circuit of relay 154 which thereupon releases to shunt the pulsing contacts of pulsing relay 101 thereby rendering the further operation of pulsing relay 101 ineiective to transmit impulses to the second selector. At its lower back contact relay 211 also opens the circuit of relay 225 which then releases, and connects ground from conductor 215 over its lower front contact, the upper front contact of relay 213 to the junction between resistance 236 and the winding of relay 214 whereupon relay 214 is shunted and releases.

Relay 225 upon releasing closes the discharge shunt around condenser 138 to fully discharge it, removes ground from the armature of pulsing relay 108 to arrest further operation of pulsing relays 101 and 188, opens the cathodeanode circuit through the tube thereby extinguishing the tube and releasing anode relay 218 and opens the locking circuits of relays 221 and 235 which thereupon release. Relay 221 upon releasing in turn releases relay 144. Re-

lay 218 upon releasing removes the shunt from the Winding of pulsing relay 141 and at its back contact establishes a shunt circuit for shunting down relay 216 as hereinbefore traced. With relay 216 released, relay 211 is locked operated in the circuit previously traced over the back contact of anode relay 218 and relay 225 is again operated over the previously traced circuit extending over the lower back contact of relay 216 and the inner lower front contact of relay 211.

Relay 225 upon reoperating removes the shunt from condenser 130; connects ground to the armature of pulsing relay 108 to 'cause relays 101 and 108 to again operate intermittently and reconnects the positive terminal of battery 211 through the winding of anode relay 218 to the anode of the tube. As soon as pulsing relay 108 engages its left contact, with re,h lay 216 released and relay 211 operated, relay 141 is operated to close the -previously traced charging circuit for dipper condenser, 151. On

the next operation of the armature of relay |08 to the right, relay |41 releases and as previously described, connects the dipper condenser in a discharging path to the bucket condenser |30. As relay |08 continues to operate, the dipper condenser |5| is alternately charged and discharged into condenser |30 until the potential across condenser |30 reaches the breakdown potential of tube ||0 whereupon the tube res establishing a discharge path for condenser |30 from the cathode ||2 to the grid as previously traced and establishing the cathodeanode circuit through the tube for reoperating the anode relay 2| 8. The time required to raise the potential on the grid of the tube to the breakdown point thus measures a sufcient delay interval to give the second selector |55 time to perform its trunk hunting function. During this time, due to the fact that relay |54 is not operated, the repeated operation of pulsing relay |01 is without effect.

When anode relay 2|8 operates it again shunts relay |41 in its non-operated position and opens the locking circuit of relay 2|1 which thereupon releases, opening at its lower contacts the locking circuit of relay 2|3 which thereupon releases, and opening the circuit of relay 225 which also releases. Relay 225 upon releasing establishes the shunt around condenser |30 to fully discharge it, removes ground from the armature of pulsing relay |08 to arrest the further operation of pulsing relays |01 and |08 and opens the cathode-anode circuit of the tube thereby extinguishing the tube and releasing anode relay 2|8.

Relay 2| 8 upon releasing removes the shunt from the winding of pulsing relay |41 and establishes the previously traced circuit for reoperating relay 2|6. With relay 2|6 operated and relay 2|1 released the previously traced circuit is established for relay 225 which reoperates to remove the shunt from condenser |30, to start the intermittent operation of pulsing relays |01 and |08 and to reconnect the positive terminal of battery 2|| through the winding of anode relay 2|8 to the anode of the tube. Upon the rst engagement of the armature of pulsing relay |08 with its left contact, with relays 2|()` and 225 now operated, relay 221 is reoperated, locks through the winding of relay i 230 as previously described and reestablishes the previously traced operating circuit for relay |44. Relay 230 operates in the locking circuit of relay 221 upon the next opening of the left contact of pulsing relay |00, causing the reoperation of relay |54 which thereupon renders the pulsing contacts of pulsing relay |01 eective for transmitting impulses to the connector switch |56.

Relay 2|3 upon releasing opens at its transfer contacts the locking circuit of steering relay 302 which thereupon releases and establishes a new holding circuit for steering relay 303 to replace the holding circuit therefor previously traced over the middle lower front contact of steering relay 302. The new holding circuit for relay 303 may be traced from battery, through the winding and inner upper front contact thereof, inner upper back contact of steering relay 30|, conductor 32|, lower normal contacts of relay 2|3 to ground on conductor 2|5. The release of steering relay 302 disconnects the register condenser 3|2 from the impulse counting device and associates register condenser 3|3 therewith.

With relay 230 operated a circuit is established from the grid of the tube, through resistance |48, condenser |30, normal contacts of key |40, conductor 239, upper front contact of relay 230, conductor 233, the upper middle back contacts of steering relays Sti and 302, the upper middle front contact of steering relay condenser 3|3, upper contacts of relay 308, conductor 229, inner lower front contact of relay 225, conductor |42, resistances i4| and E40 to ground whereby condensers i3d and 353 are ccnnected in series.

On the next operation of the armatures of pulsing relays |01 and |08 to the left, relay |01 opens the out-pulsing loop to transmit an impulse to step the connector switch |55 one step vertically and relay |08 establishes the circuit previously traced over the upper front contact of relay 2|6 and the lower front contact of relay 230 for operating the pulsing relay |41 which closes the charging circuit of dipper condenser |5|. On the next operation of the armatures of relays |01 and |08 to the right, relay |01 recloses the out-pulsing loop terminating the first impulse transmitted to connector |55, and relay |08 opens the circuit of relay |41 which now releases and connects condenser |5| into a discharge path through condenser |30. Upon successive operations of the armatures of pulsing relays |01 and |08, rst to the left and then to the right, the out-pulsing loop is opened and closed and relay |41 is operated and released to charge condenser |5| and to discharge it into condenser |30. After relay |01 has thus opened and then closed the out-pulsing loop nine times and relay |08 has operated and released relay |41 nine times, nine increments of potential will have been applied to condenser 30 at which time the total potential across the terminals of condensers |30 and 3|3 will be ten increments, since it was assumed that condenser 353 was charged with one increment of potential. This total potential applied to grid of the tube will cause the tube to break down establishing a discharge path for condensers |30 and 313 across the cathode and grid, as prevously described, and establishing a conducting path through the tube from the cathode to the anode as previously traced, over which the anode relay 2|8 is operated.

Relay 2|8 upon operating again shunts relay |41 in its non-operated position and at its back contact opens the shunt around the winding of relay 2|1. Relay 2|1 now operates, opening at its back contact the circuit of relay |54 which thereupon releases to shunt the pulsing contacts of pulsing relay |01 thereby rendering the further operation of pulsing relay |01 ineiective to transmit impulses to the connector |56, at its lower back contact opening the circuit of relay 225 which then releases, and connecting ground from conductor 2|5 over its lower front contact, the normal contacts and winding of relay 2|4, through resistance 236 to battery, whereupon relay 2|4 operates.

Relay 225 upon releasing closes the discharge shunt around condenser |30 to fully discharge it, removes ground from the armature of pulsing relay |08 to arrest further operation of pulsing relays |01 and |08, opens the cathode-anode circuit through the tube thereby extinguishing the tube and releasing the anode relay 2|8, and opens the locking circuit of relays 221 and 230 which thereupon release. Relay 221 upon releasng in turn releases relay |44. Relay 2|8 upon releasing removes the shunt from the winding of pulsing relay |41 and at its back contact establishes a shunt circuit for shunting down relay 2|5 as hereinbefore traced. With relay 2|6 released, relay 2|1 is locked operated in the circuit previously traced over the back contact of anode relay 2|8 and relay 225 is again operated over the previously traced circuit extending over the lower back contact of relay 2|6 and the inner lower front contact of relay 2|1.

Relay 225 upon reoperating removes the shunt from condenser |30,-connects ground to the armature of pulsing relay |08 to cause relays |01 and |08 to again operate intermittently and reconnects the positive terminal of battery 2|| through the winding of anode relay 2|8 to the anode of the tube. As soon as pulsing relay |08 engages its left contact with relay 2|6 released and relay 2|1 operated, relay |41 is operated to close the previously traced charging circuit for dipper condenser On the next operation of the armature of relay |08 to the right, relay |41 releases and as previously described, connects the dipper condenser |5| in a discharge path to the bucket condenser |30. As relay |08 continues to operate, the dipper condenser |5| is alternately charged and discharged into condenser |30 until the potential across condenser |30 reaches the breakdown potential of the tube whereupon the tube fires, establishing the previously traced discharging path for condenser |30 through the tube from the cathode to the grid and establishing the cathode-anode circuit to the tube for reoperating the anode relay 2|8. A time interval has thus been measured. During this time interval, due to the fact that relay |54 is not operated, the repeated operation of pulsing relay |01 is without effect.

When anode relay 2|8 operates it again shunts relay |41 in its non-operated position and opens the locking circuit of relay 2|1 which thereupon releases, opening at its lower contact the shunt around the winding of relay 2 I3 which thereupon operates, and opening the circuit of relay 225 which also releases. Relay 225 upon releasingv reestablishes the discharge shunt for condenser |30, removes ground from the armature of pulsing relay I0'8 to arrest the further operation of pulsing relays |01 and |08 and opens the cathodeanode circuit of the tube thereby extinguishing the tube and releasing the anode relay 2|8.

Relay 2|8 upon releasing removes the shunt from the winding of pulsing relay |41 and establishes the previously traced circuit for reoperating relay 2|6. With relay 2 I6 operated and relay 2 |1 released a previously traced circuit is established for relay 225 which reoperates, removes the shunt from condenser |30, starts the intermittent operation of pulsing relays |01 and |08 and reconnects the positive terminal of battery 2|| through the winding of anode relay 2|8 to the anode of the tube. Upon the rst engagement of the armature of pulsing relay |08y with its left contact, with relays 2`|6 and 225 now operated, relay 221 is operated locking through the winding of relay 230 and reestablishes the circuit of relay |44. Relay 230 operates in the locking circuit of relay 221 as soon as pulsing relay |00l opens its left contact, causing the reoperation of relay |54 which thereupon renders the pulsing contacts of pulsing relay |01 eifective for transmitting impulses to step the connector |56 in a rotary direction.

Relay 2|3 upon operating opens at its transfer contactsV the locking circuit of steering relay 303 which thereupon releases and establishes a new holding circuit for steering relay 304 to replace the holding circuit therefor previously'traced' over theV middle lower iront contact of steering relay 303.- The new holding circuit of relay 304 may beftraced from battery through the winding and inner upper front contact thereof, inner upper bac'k contact of steering relay 302, conductor 323, alternate contacts of relay 2|3 to groundY on conductor 215. The release of steeringl relay 303 disconnects the register condenser 3|3 from the impulse counting device' and associates register condenser 3|4 therewith.

With relay 230 operated a circuit is established .from the grid of tube ||0, through resistance |48, condenser |30, normal contacts'of key |40, conductor 230, upper front contact of relay 230, conductor 233', the upper middle back contacts of steering relays 30| to 303, inclusive, the upper middle front contact of steering relay 304, condenser 3|4, upper contacts of relay 300, conductor 229, inner lower front contact of relay 225, conductor |42, resistances |4| and |40 to ground whereby condensers |30 and 3|4 are connected in series.

On the next operation of the armaturesof pulsing relays |01 and |08 to the left, relay |01 opens the out-pulsing loop' to transmit an impulse to stepA the connector switch |56 one step in a rotary direction and relay |08 establishes the circuit previously traced over the upper front conta'ct of relay 2|6 and the lower front contact of relay 230 for operating the pulsing relay |41y which' closes the charging circuit of dipper condenser |5|. On the next operation of the armatures of relays |01 and |00 to the right, relay |01 closes the out-pulsing loop-to terminate the rst impulsel and relay |08 opens the circuit of relay |41 which now releases and connects condenser |5`| into a discharge path through condenser |30.- Upon successive operations of the armatures of pulsing relays |01 and |08, first to the left and then to the right, the out-pulsing loop is opened and closed and' relay |41 is operated and released to charge condenser |51 and to discharge it into condenser |30. After relay |01 has thus opened and closed the out-pulsing loop eight times and relay |08 has operated and released relay |41 eight times, eight increments of potential will have been applied to condenser |30' at which time the tota'l potential across the terminals of condensers |30 and 3|4 will be ten increments, since it wasl assumed that condenser 3|4 was charged with two increments of potential. This total potential applied to grid of the tube will c'ause the tub'e to break down establishing a discharge path for condensers |30 and 3 |4 across the cathode and grid as previously described and establishing a conducting path through the tube from the cathode to the anode as previously tip-laced, over'which the anode relay 2|8 is opera ed.

Relay 2|'8 upon operating againv shunts relay |41 in itsy non-'operated position and at its back contact opens the shunt around the winding of relay 2|1. Relay 2|1 now operates opening at its upperback contact the circuit of relay |54 which thereupon releases to shunt the pulsingA contacts of pulsing relay |01 thereby rendering the further operation of pulsing relay |01 ineffective to transmit impulses to the connector |56, at itslower back Contact opening the circuit of relay 225 which then releases and connecting ground from conductor 2|'5 over its lower front contact, the upper front contact of relay 2 I3' to the junction between resistance 236 and the winding of relay 2|4 whereupon relay 2|4 is shunted and releases.

Relay 225 upon releasing closes the discharge shunt around condenser to fully discharge it, removes ground from the armature of pulsing relay |08 to arrest further operation of pulsing relays |01 and |08, opens the cathode-anode circuit through the tube thereby extinguishing the tube and releasing anode relay 2 |8 and opens the locking circuits of relays 221 and 230 which thereupon release. Relay 221 upon releasing in turn releases relay |44. Relay 2|8 upon releasing removes the shunt from the winding of pulsing relay |41 and at its back contact establishes .a shunt around the winding of relay 2|6 as previously traced whereupon relay 2 6 releases. With relay 2|6 released, relay 2|1 is locked operated 1n the circuit p-reviously traced over the back contact of relay 2|8 and relay 225 is again operated over the previously traced circuit extending over the lower back contact of relay 2 I 6 and the inner lower front contact of relay.2|1.

Relay 225 upon operating removes the shunt from condenser |30, again starts the operation of pulsing relays |01 and |08 and reconnects the positive terminal of battery 2|| through the winding of anode relay 2|8 to the anode of the tube. As soon as pulsing relay |08 engages'its left contact, with relay 2|5 released and relay 2|'1 operated, relay |41 is operated to close the Prev1- ously traced charging circuit for dipper condenser |5|. On the next operation of the armature of relay |08 to the right, relay |41 releases and as previously described, connects condenser |5| in a discharge path to condenser |30. As relay |08 continues to operate, condenser |5| 1s alternately charged and discharged into condenser |30 until the potential across condenser |30 reaches the breakdown potential of tube 0 whereupon the tube res establishing the previously traced discharge path for condenser 30 through the tube from the cathode to the grid, and establishing the cathode-anode circuit through the tube for reoperating the anode relay 2|8. A time interval has thus been measured. During this time interval, due to the fact that relay |54 is not operated, the repeated operation of pulsing relay |01 is without effect.

Since the connector switch has now been set upon the terminals of the wanted line |02, the connector proceeds to test the line for its busy or idle condition, to return a busy signal if the line is busy, or to apply ringing current 1f the line is idle. If the line is found to be idle and the called subscriber responds, the ringing current is cut off and a talking circuit is established from the calling substation |0| to the called line |02.

When anode relay 2 i8 operates it again shunts relay |41 in its non-operated position and opens the locking circuit of relay 2|1 which thereupon releases opening at its lower contact the locking circuit of relay 2|3 which thereupon releases, and opening the circuit of relay 225 which also releases. Relay 225 upon releasing reestabllshes the discharge shunt for condenser |30, arrests the further operation of pulsing relays |01 and |08 and opens the cathode-anode circuit of the tube thereby extinguishing the tube and releasing anode relay 2 |8.

Relay 2|3 upon releasing opens at its transfer contacts one locking circuit of steering relay 304 which may be traced from battery through the winding and inner upper front contact of relay 304, inner upper back contact of steering relay 302, conductor 323, contacts of relay 2 I3 to ground on conductor 2|5 and, since it was assumed that only four digits were keyed by the subscriber and steering relay 305 has not therefore operated, there is now no effective shunt around the winding of relay 2|9 and relay 2 I9 therefore operates over a circuit extending from battery through the winding and inner lower front contact of steering relay 304, thence as traced over the inner upper normal contacts of steering relays 305 to 309, inelusive, conductor 320, winding of relay 2|9 to ground on conductor 2|5. At its contacts relay 2|9 upon operating removes ground from the armature of anode relay 2| 8 whereby relay 2|8 upon releasing is ineffective to cause the reoperation of relays 2|6 and 225 and the further operation of pulsing relays |01 and |08.

When the calling subscriber returns his handset to the cradle, ground is removed from conductor |03 thereby releasing start relay 200 which then removes ground from conductor 2|5 thereby releasing any operated relays of the sender, in this case, steering relay 304, off-normal relay 300 and relay 2|9.

Had the subscriber delayed keying after having keyed the rst digit, at which time only steering relay 30| has operated and locked under the control of the lower normal contacts of relay 2|3, off-normal relay 300 has operated and locked and the winding of relay 2 9 is shunted over the lower normal contacts of relay 2|3, the inner upper front contact of relay 30 the inner lower normal contacts of steering relays 302 to 304, inclusive, the inner upper normal contacts of steering relays 305 to 309, inclusive, and conductor 320;

then as soon as impulsing for the first digit registered in condenser register 3|| has been completed and the following time interval has been measured, relay 2|3 is operated as previously described. With no other steering relay yet operated, the operation of relay 2|3 now opens the shunt around the winding of relay 2|9 whereupon relay 2|9 operates in series with steering relay 30| in a circuit from battery through the winding and inner lower front contact of relay 30 thence over normal contacts of the remaining steering relays, conductor 320, winding of relay 2|9 to ground on conductor 2|5. Relay 2|9 upon operating removes ground from the armature of anode relay 2|9 to prevent the operation of relays 2|4 and 225 whereby the transmission of further impulses is prevented.

When the next digit is keyed and steering relay 302 operates, the winding of relay 2|9 is againA short-circuited over conductor 2| 5, the middle lower front contact of relay 30|, the inner front contacts of relay 302 and thence as traced to conductor 320, and relay 2|9 releases whereupon the out-pulsing functions of the sender are resumed in the manner previously described. A similar condition occurs at any time that the sender has pulsed out all the digits keyed by the subscriber.

From the foregoing description it will be apparent that the pairs of relays 2|6, 2|1 and 2|3, 2|4 act as counting relays, relay 2|6 operating prior to the out-pulsing of any digit series, relay 2|1 operating at the end of out-pulsing, relay 2|6 releasing prior to the beginning of the succeeding time interval and relay 2|1 releasing at the end of the time interval. Relay 2|4 operates at the end of out-pulsing for each odd digit series, relay 2|3 operates at the end of the following time interval, relay 2|4 releases at the end of the outpulsing for each even digit series and relay 2| 3 releases at the end of the following time interval.

It is to be noted thatl eight condenser registers 3|| to SIS, inclusive, are disclosed and that if a line designation comprises more than eight digits, steering relay 388 will be operated following the charging of register condenser 3|8 for the eighth digit keyed upon the release of the depressed key and will lock up and prepare a charging circuit for register condenser 3| This condenser which was employed to register the first digit keyed will by this time have determined the out-pulsing for the first digit and have become discharged. If then. the subscriber keys a ninth digit, the operation oi relay 2236, with relay 2|ll not operated will, as previously described, cause the operation of relay 2|i8 and will apply potential across the terminals of register condenser 3| I from the keyset potential divider, the left terminal of condenser 3i| being connected over the upper front contact of relay 390, conductor 2|2, the upper contacts of relay Z, conductor |132 to the junction between resistances |28 and |29 and the right terminal of condenser 3|| being connected over the lower front contact of steering relay 3&8, the lower back contact of steering relay 309, conductor 3l0, inner upper contacts of relay 206, conductor H1, left contact of the key depressed for the ninth digit to a junction between two resistances of the keyset potential divider whereby condenser 3|| will be charged to a potential determined by the digital value of the depressed key.

When the subscriber releases the depressed key, the charging path for condenser 3H is opened and relay 2% is released whereupon relay 2m operates in the locking circuit of relay 2&8, as previously described, and establishes a circuit for steering relay 393 which may be traced from battery, through the winding of relay 399, the upper front Contact of relay 3&8, conductor 3|9, upper front contact of relay Zi to ground on conductor 2de. Relay S99 upon operating locks in a circuit 'from battery through its winding and inner lower front contact, middle upper front contact oi relay 308 to ground on conductor 2|5, opens at its lower back contact the charging circuit for register condenser 3H previously traced, prepares at its middle lower front co-ntact the discharge path for condenser 3|| and establishes a new shunt around the winding of relay 2id extending, as previously traced, from thev left terminal oi relay 2|9, over conductor 323, inner front contacts of relay 389, middle upper irc-nt contact of relay 3dS, conductor 2|5 to the r'ght terminal of relay 2|9. No provision is made for registering more than nine digits although it will be apparent that the circuits might readily be arranged to do so.

The provision for enabling the registration of nine digits has particular utility when the circuits are installed on a subscribers line of a private branch exchange. In such an installation the subscriber would key a first digit to obtain access to a trunk outgoing to a central office and would then wait before keying the digits of the directory number of a desired subscribers line until after a dialing tone has been received from the central oice. rl'he establishment of the connection to the central oice restores the' rst register condenser 3H to its discharged or normal condition' as previously described. Having received the dial tone from the central o-ice the subscriber would then proceed to key the digits oi the desired line designation which might comprise seven digits to reach the subscribers linev and an eighth digit to indicate the desired party on the line should the desired subscriber be located on a party line. 'Ihe first seven digits of the line number would be registered on condensers SI2 to SIBv inclusive and the eighth digit would be registered on condenser 3|| as previously described.

Should it be found necessary to replace the tube or found desirable to check the adjustment of the tube in use, the key IM)i is first operated. The operation oi the key will connect battery over its upper alternate contacts to the ilament circuit ofl the tube and will connect both the keyset potential. divider and the pulsing potential divider across the terminals of battery 2| l. The left end of ,theV keyset potential divider is conneet-ed over conductor |3| to the positive terminal of battery 21| and the junction between resistances |23 and |29 of this potentialy divider is connected over the lower alternate contacts of key |639 and thence over conductor 2|2 to the negative terminal oi battery 2| The left end' of the pulsing potential divider is connected over conductor to the positive terminal Yor" battery 2| the negative terminal of which is connected over conductor 2|2, the neXt-to--lower alternate contacts ofkey ifi' and conductor |42 to the right terminal of the pulsing potential divider. At its inner upper alternate contacts key |49 connects the grid of tube il?) through resistance iris, over the upper back contacts of relay 225 and' resistance |38 to a test point on the keyset potential divider between resistances ||9 and |8.

After the key Idd has been operated for at least one second, test key 231 is operated thus connecting the positive terminal of battery 2|| through the winding of anode relayv2i8, contacts of key 231, back contact of relay 221 and conductor 22e to the anode of the tube. The potential applied to the grid should re the tube and if the tube is thus conducting it will be indicated by the operation of anode relay 2|8 or by the blue glow within the tube. It may then be extinguished by releasing key 231. If the tube is not conducting, the adjusting point on resistance |50 of the pulsing potential divider should be moved until the tube becomes conducting. The correct adjustment will be a point at which a minimum variation in the potential divider will distinguish between the operation and' non-operation of the tube with the key 231 operated. When the adjustment is completed both keys |49 and 231 are released.

What isclaimed is:

1. In combination, a gaseous conductor device having a definite breakdown potential, a rst condenser, means for placing a variable charge on said condenser, a second condenser, means for connecting said condensers in series in a path across the terminals of said device, a third condenser, a charging circuit for said third condenser, and means for charging said secon'd condenser in steps by connecting said third condenser alternately into said charging circuit and in parallel with said second condenser, said device becoming conducting when the sum of the charges on said first and second condensers reaches the breakdown potential of said device.

2. In combination, a gaseous conductor device having a definite breakdown potential, a rst condenser, means including a keyset for placing a charge on said condenser commensurate with the digital value of the operated key of said keyset, a second condenser, means for connecting said condensers in series in a path across the terminals of said device, athird condenser, a'

charging circuit for said third condenser, and means for charging said second condenser in steps by connecting said third condenser alternately into said charging circuit and in parallel with said second condenser, said device becoming conducting when the sum of the charges on said first and second condensers reaches the breakdown potential of said device.

3. In combination, a first condenser serving as a digit register, means including a keyset for placing a charge on said condenser commensurate with the digital value of the operated key of said keyset, means for generating impulses, an impulse counting means comprising a gaseous conductor device having a denite breakdown potential, a second condenser, means for connecting said condensers in series in a path across the terminal-s of said device, a third condenser, a charging circuit for said third condenser, means controlled by said impulse generating means for charging I said second condenser in steps by connecting said third condenser alternately into said charging circuit and in parallel with said second condenser, said device becoming conducting when the sum of the charges on said first and second condensers reaches the breakdown potential of said device, and means responsive when said device becomes conducting for arresting the operation of said impulse generating means.

4. In combination, a group of rst condensers serving as digit registers, a keyset, a group of stearing relays, means for successively operating said relays, means operated by the successive operation of said relays to successively connect said condensers with said keyset, means controlled by said keyset for placing a charge on each of said condensers when associated therewith in accordance with the digital value of an operated key, means for generating series of impulses, an impulse counting means comprising a gaseous conductor device having a definite breakdown potential, a second condenser, a third condenser, a charging circuit for said third condenser, and means controlled by said impulse generating means for charging said second condenser in steps by connecting said third condenser alternately into said charging circuit and in parallel with said second condenser, means for successively releasing said relays, means operated by the successive release of said relays to successively connect said first condensers in series with said second condenser in a path across the terminals of said device, said device becoming conducting when the sum of the charges on the second condenser and on the first condenser at the time connected in series therewith reaches the breakdown potential of said device, and means controlled by said device when it becomes conducting for terminating the impulse series then being generated.

5. In combination, a group of first condensers serving as digit registers, a keyset, a group of steering relays, means for successively operating said relays, means operated by the successive operation of said relays to successively connect said condensers with said keyset, means controlled by said keyset for placing a charge on each of said condensers when associated therewith in accordance with the digital value of an operated key, means for generating series of impulses, an impulse counting means comprising a gaseous conductor device having a definite breakdown potential, a second condenser, a third condenser, a charging circuit for said third condenser, and means controlled by said impulse generating means for charging said second condenser in steps by connecting said third condenser alternately into said charging circuit and in parallel with said second condenser, means responsive to the operation of the first of said steering relays for connecting the first of said register condensers in series with said second condenser across the terminals of said device and for starting said impulse generating means, said device becoming conducting when the sum of the charges on said first condenser and said second condenser reaches the breakdown potential of said device, means controlled by said device when it becomes conducting for restoring said impulse counting device and for releasing said first steering relay and means operated by the release of said first relay to associate the next register condenser with said counting means, said counting means functioning in this manner to successively associate said register condensers therewith until all of said register condensers are fully discharged and said impulse generating means has generated series of impulses in accordance with the charged condition of all of said register condensers.

6. In combination, a group of rst condensers serving as digit registers, a keyset, means operable to successively connect said condensers with said keyset, means controlled by said keyset for placing a charge on each of said condensers when associated therewith in accordance with the digital value of the operated key, means for generating series of impulses, an impulse counting means comprising a gaseous conductor device having a definite breakdown potential, a second condenser, a third condenser, and means controlled by said impulse generating' means for charging said second condenser in steps by alternately charging said third condenser and clischarging it into said second condenser, means operable to successively connect said iirst condensers in series with said second condenser in a path across the terminals of said device, said device becoming conducting when the sum of the charges on the second condenser and on the rst condenser at the time connected in series therewith reaches the breakdown potential of said device, means controlled by said device when it becomes conducting for terminating the impulse series then being generated, and means for operating said counting means to measure a delay interval following the generation of each series of impulses.

7. In combination, a group of rst condensers serving as digit registers, a keyset, means operable to successively connect said condensers with said keyset, means controlled by said keyset for placing a charge on each of said condensers when associated therewith in accordance with the digital value of an operated key, means for generating series of impulses, an impulse countting means comprising a gaseous conductor device having an adjustable breakdown potential, a second condenser, a third condenser, and means controlled by said impulse generating means for charging said second condenser in steps by alternately charging said third condenser and discharging it into said second condenser, means operable to connect each one of said rst condensers in series with said second condenser and said second condenser alone in alternation in a path across `the terminals of said device, said first condensers being successively connected to said second condenser, means for changing the breakdown potential of said device at such time as said second condenser only is connected across the terminals thereof, and means controlled by said device whenever it becomes conducting for arresting the operation of said impulse generating means.

8. In combination, a group of first condensers serving as digit registers, a keyset, means operable to successively connect said condensers with said keyset, means controlled by said keyset for placing a charge on each of said condensers when associated therewith in accordance with the digital value of an operated key, means for generating impulses, impulse counting means perable to alternately count series of impulses commensurate with the values of registered digits and to count series of impulses to measure interposed delay intervals, said counting means comprising a gaseous conductor device, a potential divider for varying the biasing potential of said device, a second condenser, a third condenser, and means controlled by said impulse generating means for charging said second condenser in steps by alternately charging said third condenser and discharging it into said second condenser, means operable to connect said rst condensers in succession in series with said second condenser across the terminals of said device during the counting of digit impulse series whereby said device becomes conducting to terminate the counting of any impulse series when the total potential across the second condenser and the associated first condenser reaches the critical breakdown potential of said device, and means for connecting said second condenser only across the terminals of said device during the counting of impulses for a delay interval whereby said device becomes conducting to terminate the counting for the delay interval when the potential across said second condenser reaches the critical breakdown potential of said device.

9. In combination, a rst condenser serving as a digit register, means including a keyset for placing a charge on said condenser commensurate with the digital value of the operated key of said keyset, means for generating impulses, an impulse counting means operable first to count a series of impulses commensurate with the value of the registered digit and then to count a series of impulses to measure a delay interval comprising a gas-filled tube having an anode, a cathode and a grid, a potential divider for varying the biasing potential on the grid of said tube, a second condenser, a third condenser, and means controlled by said impulse generating means for charging said second condenser in steps by alternately charging said third condenser and discharging it into said second condenser, means operative to start said impulse generating means and to connect said rst condenser in series with said second condenser across the cathode-grid path through said tube to one point on said potential divider whereby said tube is caused to become conducting when the sum of the charges on said first and second condensers reaches the critical breakdown potential of said tube, an anode relay operable over the cathode-anode path through said tube when said tube becomes conducting to arrest the operation of said im pulse generating means and to extinguish said tube, means controlled by said latter means to restart said impulse generating means and to connect said second condenser across the cathode-grid path through said tube to another point on said potential divider whereby said tube is again caused to become conducting when the charge on said second condenser reaches the critical breakdown potential of said tube, said anode relay then again operating to arrest the operation of said impulse generating means.

10. In a register in which a digit is recorded as a quantity of charge on a condenser, means for determining the value of the recorded digit comprising, means for connecting a potential in series with said condenser and varying the value of said potential in substantially uniform steps, the number of steps required to cause the effective total potential to arrive at a predetermined value thus being a measure of the charge on the condenser and hence characteristic of the digit recorded.

1l. In combination, two condensers, means for charging the first of said condensers to any of a plurality of different values, means for charging the second of said condensers in substantially uniform steps, a discharge path, means for connecting said two condensers in series in said discharge path after each of said steps, means preventing the discharge of said condensers over said path until said second condenser has been charged to a value complementary to the value of the charge upon said first condenser, and means operated by the discharge of said condensers over said path when said second condenser has been charged to said complementary value.

12. In combination, two condensers, means for charging the rst of said condensers to any of a plurality of diierent values, means for charging the second of said condensers in steps and, after each step, testing the effective total potential of said two condensers in series, means substantially preventing any variation in the amount of charge on said first condenser during each of said testing operations if said effective total potential is below a predetermined value, and means operated when the eiective total potential of the two condensers in series reaches said predetermined Value.

FREDERICK R. LAMBERTY. GEORGE W. WEAVER. 

